Iodine and Selenium: Importance, Benefits, and Sources

Iodine and selenium are two essential minerals that play a vital role in maintaining optimal health. While iodine is necessary for the proper functioning of the thyroid gland, selenium is a powerful antioxidant that supports the immune system and helps protect the body against oxidative stress.

The human body requires iodine to produce thyroid hormones that regulate metabolism, growth, and development. Iodine deficiency is a significant public health problem worldwide, affecting millions of people. It can lead to a range of health problems, including goiter, hypothyroidism, cretinism, and intellectual disability.

Selenium deficiency is also a widespread problem, especially in areas where the soil is deficient in this mineral. Selenium plays a crucial role in the body’s antioxidant defense system, protecting cells from oxidative damage caused by free radicals. It also supports the immune system, helps regulate thyroid hormones, and is essential for fertility and reproduction.

Iodine and Selenium Deficiencies

Iodine and selenium are two essential minerals that are required for optimal thyroid function. Deficiencies in either of these minerals can lead to a range of health problems.

Iodine Deficiency

Iodine deficiency is a major public health problem, affecting over 2 billion people worldwide. Iodine is required for the production of thyroid hormones, which regulate metabolism, growth, and development. Without enough iodine, the thyroid gland cannot produce enough thyroid hormones, leading to hypothyroidism.

Common symptoms of iodine deficiency include fatigue, weight gain, cold intolerance, dry skin, hair loss, and a hoarse voice. In severe cases, iodine deficiency can lead to goiter, cretinism, and intellectual disability.

Selenium Deficiency

Selenium deficiency is less common than iodine deficiency, but it can also have serious health consequences. Selenium is required for the production of selenoproteins, which play a vital role in antioxidant defense, immune function, and thyroid hormone metabolism.

Common symptoms of selenium deficiency include muscle weakness, fatigue, cognitive decline, and an increased risk of viral infections. In severe cases, selenium deficiency can lead to Keshan disease, a type of heart disease that is endemic in certain parts of China.

There is also evidence to suggest that selenium deficiency can exacerbate iodine deficiency, potentially increasing the risk of cretinism in infants.

Sources of Selenium and Iodine

Food Sources

Selenium and iodine are essential minerals that the human body needs to function properly. They can be obtained from a variety of food sources.

Brazil nuts, seafood, and organ meats are the richest food sources of selenium. Other sources include muscle meats, cereals and other grains, and dairy products. Americans obtain most of their selenium from everyday staples, like bread, cereals, poultry, red meat, and eggs.

Iodine-rich foods include dairy, seaweed, certain fish, beans, and fruit. The thyroid gland needs iodine to produce thyroid hormones, which have many important functions in the body.

Iodine and Selenium Supplements

While it is possible to get enough selenium and iodine from a healthy, balanced diet, some people may need to take supplements to meet their daily requirements.

Iodine supplements are available in both tablet and liquid form. The recommended daily intake of iodine for adults is 150 mcg per day. However, it is important to talk to a healthcare provider before taking any iodine supplements, as too much iodine can be harmful.

Selenium supplements are also available in tablet form. The recommended daily intake of selenium for adults is 55 mcg per day. However, taking too much selenium can also be harmful, so it is important to talk to a healthcare provider before taking any supplements.

Overall, a balanced diet that includes a variety of nutrient-dense foods is the best way to ensure that the body gets the necessary amounts of selenium and iodine. However, for those who may not be able to obtain enough from their diet alone, supplements may be a helpful addition.

Functions of Iodine and Selenium

Iodine Functions

Iodine is an essential mineral that plays a crucial role in the production of thyroid hormones. The thyroid gland needs iodine to produce the hormones that regulate the body’s metabolism, growth, and development. Iodine deficiency can lead to hypothyroidism, which is characterized by low levels of thyroid hormones in the body.

In addition to its role in thyroid function, iodine also plays a role in fetal and infant brain development. Pregnant and breastfeeding women need more iodine to ensure their babies’ healthy brain development. Iodine deficiency during pregnancy can lead to intellectual disabilities and other developmental problems in the baby.

Selenium Functions

Selenium is a mineral that is important for many bodily functions, including thyroid function. Selenium is required for the conversion of thyroid hormones from inactive to active forms. It also helps protect the thyroid gland from damage caused by oxidative stress.

Selenium is also an important antioxidant that helps protect cells from damage caused by free radicals. It plays a role in the immune system by helping to regulate inflammation and supporting the function of immune cells.

Selenium may also play a role in reducing the risk of certain diseases, such as heart disease and some types of cancer. However, more research is needed to fully understand the potential health benefits of selenium.

Recommended Intake of Iodine and Selenium

Iodine Recommended Intake

Iodine is an essential nutrient that the body needs to produce thyroid hormones. The recommended daily intake of iodine varies depending on age and life stage. According to the National Institutes of Health, the recommended daily intake of iodine is:

  • Birth to 6 months: 110 mcg
  • Infants 7-12 months: 130 mcg
  • Children 1-8 years: 90 mcg
  • Children 9-13 years: 120 mcg
  • Teens 14-18 years: 150 mcg
  • Adults 19 years and older: 150 mcg
  • Pregnant women: 220 mcg
  • Lactating women: 290 mcg

It’s important to note that some individuals may require higher doses of iodine, such as those who live in areas with low levels of iodine in the soil or who have had their thyroid removed. However, excessive iodine intake can also be harmful, so it’s important to speak with a healthcare provider before taking iodine supplements.

Selenium Recommended Intake

Selenium is a trace mineral that plays an important role in the body’s antioxidant defense system. The recommended daily intake of selenium also varies depending on age and life stage. According to the National Institutes of Health, the recommended daily intake of selenium is:

  • Birth to 6 months: 15 mcg
  • Infants 7-12 months: 20 mcg
  • Children 1-3 years: 20 mcg
  • Children 4-8 years: 30 mcg
  • Children 9-13 years: 40 mcg
  • Teens 14-18 years: 55 mcg
  • Adults 19 years and older: 55 mcg
  • Pregnant women: 60 mcg
  • Lactating women: 70 mcg

It’s important to note that consuming too much selenium can also be harmful. The tolerable upper intake level for selenium is 400 mcg per day for adults. Consuming excessive amounts of selenium can cause symptoms such as hair loss, nail brittleness, and gastrointestinal upset. As with iodine, it’s important to speak with a healthcare provider before taking selenium supplements.

Iodine and Selenium Toxicity

Iodine Toxicity

Excessive intake of iodine can lead to iodine toxicity, also known as iodism. Symptoms of iodism include burning of the mouth, throat, and stomach, as well as fever, headache, and metallic taste. Severe cases can result in swelling of the salivary glands, nausea, vomiting, and diarrhea.

Iodism is rare in the United States due to the widespread use of iodized salt, which provides a consistent source of iodine. However, excessive intake of iodine-containing supplements or foods can still lead to iodine toxicity. The tolerable upper intake level for iodine is 1,100 mcg per day for adults.

Selenium Toxicity

Chronic high intake of selenium can lead to toxicity, which can result in a range of health problems. Mild symptoms include hair loss, nail brittleness, and skin rash. More severe outcomes include muscle tremors, stomach upset, and lightheadedness, as well as heart attack, respiratory distress, or kidney failure.

The tolerable upper intake level for selenium is 400 mcg per day for adults. It is important to note that selenium toxicity is rare in the United States and is more commonly associated with areas where the soil is naturally high in selenium, such as parts of China and Russia.

It is important to consume iodine and selenium in appropriate amounts to maintain good health. While toxicity is rare, excessive intake of these nutrients can have negative consequences. It is recommended to obtain these nutrients through a balanced diet and to consult a healthcare professional before taking supplements.

Conclusion – Selenium with Iodine

Selenium and iodine are two essential micronutrients that play a critical role in thyroid function and overall health. The research suggests that both minerals are required for optimal thyroid hormone synthesis and function. Iodine is an essential component of thyroid hormones, and its deficiency is considered the most common cause of preventable brain damage in the world. On the other hand, selenium is essential for the conversion of thyroid hormones and has antioxidant properties that help protect the thyroid gland from oxidative stress.

Studies have shown that a deficiency in either mineral can have negative effects on thyroid health. A lack of iodine can lead to hypothyroidism, which can cause symptoms such as weight gain, fatigue, and depression. A deficiency in selenium can lead to thyroid enlargement and an increased risk of thyroid disease.

It is important to note that while both minerals are essential for thyroid health, excessive intake of either mineral can be harmful. High levels of iodine can lead to thyroid dysfunction, while high levels of selenium can lead to toxicity. Therefore, it is crucial to maintain a balance of both minerals in the diet.

There are several dietary sources of iodine and selenium, including seafood, dairy products, eggs, and nuts. However, the amount of these minerals in food can vary depending on the soil and water content in the region where the food is grown. Therefore, it may be necessary to supplement the diet with iodine and selenium to ensure adequate intake.

In conclusion, selenium and iodine are two essential minerals that play a crucial role in thyroid health. Both minerals are required for optimal thyroid hormone synthesis and function, and a deficiency in either mineral can have negative effects on thyroid health. It is important to maintain a balance of both minerals in the diet to ensure optimal thyroid health.

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About the Author Adam


As a health and fitness writer, Adam combines his two passions—weightlifting and writing. With a creative writing degree under his belt, he spends his mornings lifting weights, his nights putting pen to paper, and eating too many snacks in between.

Health Disclaimer

  • Any products written about is not intended to diagnose, treat, cure, or prevent any disease.
  • Results may vary/may not be typical. 
  • This information does not constitute medical advice and it should not be relied upon as such. Consult with your doctor before modifying your regular medical regime.

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